Auxiliary charge pump for a rectifier of an RFID transponder

Abstract

The present invention relates in one aspect to an auxiliary charge pump for a RFID rectifier, the charge pump, which comprises a first charge pump stage ( 11; 111 ) connected to an input ( 14; 114 ), a second charge pump stage ( 12; 112 ) connected to the input, a diode clamp ( 13; 113 ) connected to an output ( 15; 115 ), and a regulating transistor ( 16; 116 ) having a gate connected with an output ( 21; 121 ) of the first charge pump stage and having a source and a drain, wherein one of the source and the drain is coupled to the diode clamp. In further aspects the invention relates to a RFID transponder, to a multistage rectifier and to a rectifier stage comprising such an auxiliary charge pump.

The invention claimed is: 
     
       1. An auxiliary charge pump for a rectifier, the auxiliary charge pump comprising:
 a first charge pump stage connected to an input, 
 a second charge pump stage connect to the input, 
 a diode clamp connected to an output, and 
 a regulating transistor having a gate connected with an output of the first charge pump stage and having a source and a drain, wherein one of the source and the drain is coupled to the diode clamp, 
 wherein the diode clamp comprises multiple diode clamp transistors connected in series, and 
 wherein the source or the drain of the regulating transistor is connected to a node located between the drain and source of two diode clamp transistors. 
 
     
     
       2. The auxiliary charge pump according to  claim 1 , wherein the regulating transistor is an NMOS transistor, and wherein the drain of the regulating transistor is coupled to the diode clamp. 
     
     
       3. The auxiliary charge pump according to  claim 2 , wherein the source of the regulating transistor is connected to ground. 
     
     
       4. The auxiliary charge pump according to  claim 1 , wherein the regulating transistor is a PMOS transistor, and wherein the source of the regulating transistor is coupled to the diode clamp. 
     
     
       5. The auxiliary charge pump according to  claim 4 , wherein the drain of the regulating transistor is connected to ground. 
     
     
       6. The auxiliary charge pump according to  claim 1 , wherein the gates of the diode clamp transistors are connected in parallel. 
     
     
       7. The auxiliary charge pump according to  claim 6 , wherein the gates of the diode clamp transistors are connected to an output node of the second charge pump stage. 
     
     
       8. The auxiliary charge pump according to  claim 1 , wherein the first and the second charge pump stages each comprise at least a first transistor and a second transistor, wherein the first and second transistors are native metal-oxide-semiconductor field-effect transistors. 
     
     
       9. The auxiliary charge pump according to  claim 8 , wherein a gate and a source of the second transistor is connected to an input node of the first or second charge pump stage, and wherein a drain of the first transistor is connected to the input node. 
     
     
       10. The auxiliary charge pump according to  claim 9 , wherein a drain of the second transistor is connected to an output node of the first or second charge pump stage. 
     
     
       11. The auxiliary charge pump according to  claim 10 , wherein the output node of the first charge pump stage is connected at least to a gate or to a drain of the first transistor of the second stage. 
     
     
       12. A rectifier stage comprising:
 a PMOS transistor, 
 an NMOS transistor, wherein a drain of the NMOS transistor and a source of the PMOS transistor are connected to an input node, 
 a first auxiliary charge pump connected to a gate of the NMOS transistor, and 
 a second auxiliary charge pump connected to a gate of the PMOS transistor, 
 wherein the first auxiliary charge pump is an auxiliary charge pump for a rectifier, the auxiliary charge pump comprising: 
 a first charge pump stage connected to an input, 
 a second charge pump stage connect to the input, 
 a diode clamp connected to an output, and 
 a regulating transistor having a gate connected with an output of the first charge pump stage and having a source and a drain, wherein one of the source and the drain is coupled to the diode clamp. 
 
     
     
       13. A multistage rectifier comprising at least two rectifier stages according to  claim 12 . 
     
     
       14. A transponder, comprising an antenna, a controller and a multistage rectifier according to  claim 13 .